Vane lapping fixture



March 1, 1960 H. c. DEAN ET AL VANE LAPPING FIXTURE Filed Nov. 20, 1958 INVENTORS HARRY c. DEAN VIRGIL J. PEDERSON f TTORNEYS VANE LAPPING FIXTURE Harry C. Dean, San Leandro, and Virgil J. Pederson,

' Centerville, Calif.

Application November 20, 1958, Serial No. 775,326

, 6 Claims. .(Cl. 51-234) (Granted' under Title 35,05. Code (1952 seegzsa The invention described .herein may be manufactured .115

and.used by. or for the Government of the Umted States of America for governmental'purposes without the payment of any royalties thereon or therefor.

This invention relates to fixtures and more specifically to a fixture for lapping work pieces, such as blades or vane-type pumps, on a'conventional lapping machine.

It is a conventional practice in the art to regrind worn blades or vanes of rotary pumps. Heretofore, the grinding was accomplished by hand on an individual piece basis. This method ,hasthe obvious disadvantages of being time consuming, lacking precision and uniformity; and, furthermore, is unsuitable for regrinding badly worn blades. The fixture of the present invention enables a plurality of blades to be lapped simultaneously, thus ensuring precision and uniformity.

The fixture comprises a frame suspended over a conventional lapping machine, the frame supporting a reciprocable blade holder or rack, preferably rake-shaped. The vanes are supported loosely in a vertical position between adjacent tines of the rake with the edge to be ground resting in contact on the lapping surface. As the work holder is reciprocated by a suitable driving means, a rolling or rocking action is imparted to the blades during the lapping operation to provide the desired contour to edges of the blades.

A principal object of this invention is to provide a fixture for use on a lapping machine that will support a plurality of work pieces having working edges, and to impart a motion to said work pieces during the lapping operation to provide such edges with a predetermined contour.

Further objects are to provide a fixture for lapping a plurality of blades simultaneously, uniformly, and with a precision-formed working edge.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a front elevation view of the fixture, partially in section to show the nested work holder, suspended over a lapping machine;

Fig. 2 is a cross section taken along line IIII of Fig. 2; and

Fig. 3 shows two enlarged views of the work holder at opposite ends of the reciprocating motion.

Referring to the drawing where like reference numerals refer to the same parts throughout the figures, there is shown in Fig. 1 a novel fixture supported over a portion of a rotary lapping wheel 12 of a conventional lapping machine 14, such as a Lapmaster 24 manufactured by the Crane Packing Company. The lapping machine forms no part of this invention and, it is apparent the invention fixture can be used on other types of machines.

Fixture 10 comprises a U-shaped channeled frame 16 'ice having a bottom wall 18 andtwo side walls 20 secured by screws 22 to two oppositely disposed end plates 24 mounted to the lapping machine by integral uprights 26. Bottom wall 18 consists of a plurality of spaced, transversely disposed tines 28 arranged to support freely therebetween the working edge end of a pump vane 30. Tines 28 are preferably half round rods welded or otherwise secured to the side walls to provide a camming action with respect to the vanes. A vertical slot 32 is formed .in both ends of each side wall 20 for a purpose to be "described.

A U-sha'ped' work holder or rack 34, having a bottom wall 36 and'side walls "suspended within frame 16' by'a pair of;invcrt edyokes-40, one at each end of the frame. similarly tofbottonr wall 18 of frame16, bottom wall "36 consists-"of:a pluraiity of spaced tines 42 which freely support therebetween-an upper portion of the re-- spective 'vanes30 inispaced relation to the tines 28. The height of bottom wall 36 above bottom wall 18 can be varied by adjustment ofyokes 40.

Each yoke includes} a base portion 44 having depending leg portions 46, the former being supported centrally on end plates 24 by an adjusting screw 48 threadedly extending therethrough; The upper end of screw 48 has a knurled fin ger-engaging portion 50 and the opposite tions 46 straddle frame walls 20, and are provided at their lower ends with a pair of integral spaced rails 56 which project inwardly through and are movable in slots 32 of the frame. Rails 56 slidably accommodate a horizontal lug 58 integrally mounted on the outside of walls 38 of the work holder for suspending the latter in spaced relation to the frame and for also permitting the Work holder to be reciprocated therein by any suitable drive mechanrsm.

Work holder 34 can be reciprocably driven by any suitable driving means, such as an air motor 60 connected by hose 62 to a source of air pressure, not shown. Motor 60 is connected to an eccentric cam 64 through a bevel gearing 66, the cam 64 extending through a corresponding aperture 67 in the work holder and journaled to an extension 68 of frame 16. A spring 70 biases cam 64 in contact with aperture 67.

Operation of the fixture is as follows. With the fixture suspended over lapping wheel 12, the worn pump vanes 30 are dropped, with the working edges downward, between the corresponding pairs of tines in the work holder and the frame. As the lapping wheel is rotated, work holder 34 is reciprocated by the drive mechanism causing the upper portion of the vanes supported between tines 28 to be rocked back and forth about the working edges of the vanes being confined between tines 42, as illustrated in Figs. 3a and 3b. The working edges of the vanes are simultaneously lapped with a curvature having an extent depending on the amount of throw, or the distance between the two sets of tines as adjusted by yokes 40. The rounded upper surfaces of the tines enable the vanes to roll smoothly during the rocking action.

The invention fixture provides an expedient means for lapping simultaneously a plurality of vane type pump blades on a conventional lapping machine with precision and uniformity.

We claim:

1. A fixture for supporting pump vanes on a lapping machine having a grinding surface comprising a frame adapted to be supported over said grinding surface, a rack reciprocably mounted within said frame, said rack and frame having means for laterally supporting therebetween a plurality of spaced vertical pump vanes each having a curved edge tobe lapped by the'grindin'gsurface, said frame means providing bearing surfaces about which the vanes are pivotable, said rack "supporting said vanes in spaced relation to said frame, and means for reciprocating said rack in agplane parallel to said grinding surface whereby a rocking motion, is, imparted to the, sup.- ported vanes about said frame during the; lapping operation to provide said working edgesfwith a predetermined curved contour.

2. The fixture of claim 1' wherein means, are. provided for varying the amount of throw of said vanes in the rocking movement.

3. The fixture of claim lwhereinmeansare. provided for vertically adjusting said rack on. said frame tQ-vary the amount of throw of said vanes in the rocking act-ion,

4. A fixture for supporting pumpvanes 01.1.. a lapping machine having a grin ing, rface, comprising, a tr m adapted to be supported over surface, 'a rack reciprocably mounted in, said frame, in. Spaced rclaf. tion, above said grinding surface; said-raclt'having 8121.11.- rality of vertical openings each, openingloosely to. re.- ceive a vane having a curved. edge. adapted to. engage. said grinding surface and, be. lapped thereby, means, on the frame having bearing surfaces about which the. vanes are pivotable, means for reciprocating said" hack in. a plane parallel to said grinding surface whereby a rock.- ing motion is imparted to the supported vanes. substantially about saidframe to provide said vane, ends with a predetermined curved contour.

5. The vane fixture. device. oi'claim 4: wherein said.

frame is provided with a plurality ofvertical openings substantially aligned with the openings on said rack, said frame means being disposed between said rack and the grinding surface.

6. A pump vane fixture for use on a lapping machine having a grinding surface, comprising a frame adapted to be supported over and adjacent said grinding surface, said frame having a bottom wall provided with a plurality of vertical recesses, a rake-shaped rack reciprocably mounted in said frame in spaced relation above the bottom wall of the frame, said rack having a bottom wall provided with a plurality of recesses to be vertically aligned with corresponding recesses on said frame, each vane being loosely disposed within the respective recesses to be supported by and between said rack and said frame, each. vane having a curved. edge. adapted to engage said grinding surface and be lapped thereby, means for reciprocating said rack in a plane parallel to said grinding surface whereby the supported vanes have imparted to. them a rocking motion substantially about said bottom wall of the. frame to provide a predetermined curved contourto the. edge. of the vane.

References Cited in the file of. this, patent UNITED STATES PATENTS 989,122 Collins Apr. 11, 1911 FOREIGN PATENTS 232 691 Germany -4 Mar. 1'8, 1911 

